Banning XYCraft tanks would be doable, but difficult logistically.
I currently have three such tanks (two of them with contents at the moment), and while I'm happy to replace them with railcraft tanks, one of them is my lava which I'd need to supply the energy to build the replacement tanks.
It's a bit chicken/egg ... I need the contents of the tank to let me replace the tank.
I might have enough iron on hand to do the job, but probably not.
The other side of the equation isn't viable. I moved over 4k from spawn to get away from the bunched up nether portals and I really don't want to have to share portals and spend hours wandering the nether looking for lava source to pump, which is what would happen if we had a shared portal at spawn.